The long-term goals of this research are to understand the adaptive and compensatory capabilities of the gaze stability systems following vestibular lesions and to identify the mechanisms that drive the compensation process. An understanding of the adaptive/compensatory mechanisms will be pertinent to motor learning, a fundamental question in neuroscience, and will have practical implications for our understanding of how humans compensate for vestibular disorders. A functional, long-term outcome of this research will be the development of more appropriate rehabilitation strategies for patients with vestibular disorders. These rehabilitation strategies may serve as models for the rehabilitation of other neuromuscular movement disorders. The first aim of the study is to determine the mechanism(s) responsible for improvements in gaze stability during head movements following unilateral vestibular loss. Gaze stability during head movements will be measured using a computerized dynamic visual acuity (DVA) system. Eye movements will be recorded using a video based eye movement recording technique during the DVA test prior to and following the completion of a vestibular rehabilitation program. The eye movements for successful and unsuccessful trials will be characterized. The eye movements post-rehabilitation will be analyzed to determine if there has been an improvement in the vestibulo-ocular reflex gain, an increase in the use of vestibular catch-up saccades, and/or an increase in the use of anticipatory slow eye movements. The second aim of the study is to determine if there is a difference in the efficacy and nature of recovery in individuals with unilateral vestibular loss who are given a rehabilitation program consisting of either vestibular adaptation exercises or a program of vestibular habitation exercises. The recovery will be assessed using DVA, eye movement recording, measures of motion sensitivity, balance and gait function, as well as subjective measures of function and impairment. [unreadable] [unreadable] [unreadable]